This invention relates generally to turbochargers and related methods of assembly. More specifically, this invention relates to an improved turbocharger construction adapted for rapid and easy assembly of turbocharger components along a single axis at a single work station.
Turbochargers and turbocharger systems in general are known for supplying a combustion engine with a charge of air under pressure, commonly referred to as charge air. The turbocharger typically comprises a turbine wheel and a compressor impeller mounted for rotation with a common shaft. The turbine wheel and compressor impeller are positioned within turbine and compressor housings, respectively, which are in turn normally connected to a so-called center housing including appropriate bearing components for supporting the rotating shaft. Exhaust gases from a combustion engine are coupled for passage through the turbine housing to rotatably drive the turbine wheel, whereby the rotating turbine wheel corresponding drives the compressor impeller to compress ambient air for supply as charge air to the engine air intake. This flow of compressed charge air effectively increases the total mass flow through the engine to permit engine operation at increased performance levels with increased power output.
In the past, turbocharger design efforts have focused predominantly upon improvements in aerodynamic performance and mechanical operation. In particular, significant design efforts have been directed toward enhancing aerodynamic efficiency with respect to the turbine wheel and/or the compressor impeller and their related gas flow passages through the turbine and compressor housings. Other substantial design activity has been directed toward improvements in bearing design and lubrication to achieve high speed shaft rotation with prolonged operating life. Relatively minimal design activity has focused upon simplification of the turbocharger components for purposes of easier component assembly with significantly reduced labor time.
More specifically, according to conventional turbocharger constructions, modern turbochargers are assembled by a succession of relatively complex and tedious steps which require significant special handling and the use of customized tools. In a typical assembly process, a turbine wheel and integral shaft are initially assembled with the center housing in combination with appropriate journal and thrust bearing components. The compressor impeller is then attached to the shaft to produce a center housing rotating subassembly. This subassembly is subsequently coupled with appropriate turbine and compressor housing components to complete the turbocharger construction. Unfortunately, this assembly sequence requires the center housing to be inverted several times as the various components are mounted in place. As the assembly process proceeds, the partially assembled turbocharger is normally transferred through a sequence of work stations having unique custom support fixtures. Moreover, a variety of mounting bolts or the like are required to be installed at locations which are difficult to reach and/or often require customized tools to tighten the bolts. As a result, assembly of the turbocharger components entails significant manual labor and time.
The above-described complexities relating to turbocharger manufacturing processes yield corresponding disadvantages in the repair or rebuilding of used turbochargers. More specifically, in operation, a turbocharger is normally mounted at a relatively confined position on or adjacent to a combustion engine. The space limitations have generally prohibited partial disassembly of the turbocharger for repair or maintenance, without first removing the entire turbocharger unit from the engine. Once removed, the turbocharger must be disassembled for repair and then re-assembled according to the same inefficient methods used for original manufacture.
The present invention provides an improved turbocharger assembly which is specifically designed to facilitate the manufacturing process by significantly reducing the time and labor involved in the assembly of turbocharger components. In particular, the turbocharger assembly of the present invention provides a plurality of components adapted for stack-up installation along a single axis at a single work station.